Many current integrated circuits are formed as multiple dies on a common wafer. After the basic process steps to form the circuits on the dies are complete, the individual dies are singulated from the wafer. The singulated dies are then usually mounted to structures, such as circuit boards, or packaged in some form of enclosure.
One frequently-used package consists of a substrate upon which a die is mounted. The upper surface of the substrate includes electrical interconnects. The die is manufactured with a plurality of bond pads. A collection of solder joints are provided between the bond pads of the die and the substrate interconnects to establish ohmic contact. After the die is mounted to the substrate, a lid is attached to the substrate to cover the die. Some conventional integrated circuits, such as microprocessors, generate sizeable quantities of heat that must be transferred away to avoid device shutdown or damage. The lid serves as both a protective cover and a heat transfer pathway.
Stacked dies arrangements involve placing or stacking one or more semiconductor dies on a base semiconductor chip. In some conventional variants, the base semiconductor die is a high heat dissipating device, such as a microprocessor. The stacked dies are sometimes memory devices. In a typical conventional manufacturing process the dies are stacked one at a time on the base die. Die-to-die electrical connections are by way of bumps and through-chip-vias.